The Fed has spent the past three years on a route of aggressive rate cuts and purchases of trillions in various securities but it is running out of measures it can take, Pimco's co-CEO Mohamed El-Erian told CNBC.

Wermuth is a fund manager heavily invested in Russia and says if the same International Monetary Fund (IMF) team that managed the financial crisis in the former super power in 1998 now turned up at the US Treasury, they would withdraw support for current US policy immediately.

"The big evil for the IMF in Russia in 1998 was the prospect of the central bank funding government debt. The Fed is now even buying mortgage-backed securities," he noted.

"Even before the (Troubled Asset Relief Program) and the expansion of the Fed's balance sheet, total US public and private debt as a percentage of GDP in the US stood at 290 percent, that figure is now far higher," Wermuth added.

"US credit risk is huge and America has two options, either default or let the currency depreciate substantially against currencies such as the yuan and the rouble," he explained.

"Last night's news from the Fed simply creates the right conditions for dollar weakness and a reduction in US liabilities to foreign investors and governments," Wermuth said.

(CORRECTION: An earlier version of the story quoted Wermuth as saying total US government debt as a percentage of GDP was 290 percent. Wermuth said the ratio of total US public and private debt is 290 percent.)